Submitted to: International Congress of Plant Molecular Biology
Publication Type: Abstract Only
Publication Acceptance Date: July 15, 2003
Publication Date: September 1, 2003
Citation: Rajasekaran, K. 2003. Cotton cells transformed by oncogenic agrobacterium strains facilitate a rapid gene expression assay for input traits [abstract]. International Congress of Plant Molecular Biology. S10-109:168. Technical Abstract: Cotton cells transformed by oncogenic Agrobacterium strains facilitate a rapid gene expression assay for input traits K. Rajasekaran A simple expression assay for evaluation of gene constructs for input traits into cotton cells (Gossypium hirsutum L.) using oncogenic Agrobacterium strains is presented. Explants from three commercial cotton varieties, representing diverse genotypes, exhibited tumor or root formation to an equal degree in response to infection by different types of oncogenic Agrobacterium strains. Cotyledon explants readily developed tumors (100%) within a week and the tumors doubled in fresh weight every two weeks. A. rhizogenes super-rooting mutant strain MT232 was highly infective on cotyledon explants. Experiments with oncogenic strains served as a basis for development of an assay using tumor-inducing binary vectors carrying the gene to be evaluated, a truncated Bacillus thuringiensis (Bt) cryIA(c) insecticidal crystal protein (ICP) gene. The efficacy of the truncated ICP gene was first demonstrated using transgenic tobacco plants challenged with the Lepidopteran pest, tobacco hornworm (Manduca sexta). An oncogenic binary vector containing a chimeric neomycin phosphotransferase II and the Bt ICP gene conferred antibiotic resistance and pesticidal activity against Lepidopteran larvae to tumor cells from cotyledon explants. The effective expression and pesticidal activity of the ICP gene towards control of a Lepidopteran cotton pest, tobacco budworm (Heliothis virescens), was demonstrated in this study using cotton tumor cells. The time needed to conduct the experiment with cotton tumor cells was about three to four months from the time of initiation, equivalent to the time needed for the tobacco model system. The rapidity of this assay is extremely useful in evaluation of gene constructs for input traits in the laboratory, especially in recalcitrant species such as cotton, where more than 15 months are needed for selection and regeneration of transgenic plants.